Blade attachment



2 Sheets--Shee'l'l 1 G. J. Hun-:BNERQ JR., Er AL BLADE ATTACHMENT July13, 1954 Filed sept. 1, 1948 1N VENOR 5.

wertig. Berufen July l31954 G. J. HUEBNER, JR., Er AL w 2,683,583

BLADE ATTACHMENT Filed Sept. l, 1948 2 Sheets-Sheet 2 Patented July 13,1954 UNITED it'iNT OFFICE BLADE ATTACHMENT Application September 1,1948, Serial No. 47,174

3 Claims.

The present invention relates to blading, and more particularly toblading of the side entry type for use in elastic iiuid utilizingapparatus and has for an object the provision of an improved fasteningmeans for blading of this character.

Another object of the invention is to provide novel securing means forretaining a side entry blade in its mating rotor groove, which securingmeans can be released and the blade removed without necessarilyaifecting the securing means for all other blades in its row.

Still another object of the invention is to provide novel securing meansfor side entry blades of elastic fluid utilizing apparatus, whichsecuring means can be released to permit removal of and re-insertion ofany desired blade without disturbing the setting of adjacent blades.

A further object is to provide a blade attachment such that its carriermay bear the conguration of a large hollow cylinder or frustum and havethus imparted to it an inherent lightness along with a naturalstructural rigidity.

Still a further object is to produce a blade structure wherein thecarrier lends itself to a single integral casting construction which issimplel and relatively cheap to produce.

Yet a further object is to produce blade structure susceptible of readyand easy insertion and removal.

Yet another object is to avoid the undue Weakening of the spindlethrough the formation therein of the spaces intended for theaccommodation of the blades.

While blade-fastening means of the character hereinafter disclosed willbe found useful in many situations and types of apparatus, it isparticularly useful in compressor and turbine apparatus for gas turbinepower plants.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings forming a part of this application inwhich:

Fig. 1 is a longitudinal view of apparatus embodying the presentinvention, portions of the apparatus being broken away for the sake ofclearness;

Fig. 2 is a fragmentary plan view of a compressor drum showing a row ofimpeller blades partially broken out and flanked by the strips relievedto accommodate the companion guide vanes;

Fig. 3 is a fragmentary transverse section through the compressor drumshown in Fig. 2;

Fig. 4 is a fragmentary perspective View of the compressor drum shown inFigs. 2 and 3 and brings out details of the securing and lockingarrangement provided for the blades;

Fig. 5 is a view similar to Fig. 3, but shows how the invention may beapplied to a tapered drum; and

Fig. 6 is a perspective view of a moving blade as appears in theassembly showing of Fig. 5.

The phraseology or terminology employed herein is for the purpose ofdescription and not of limitation and it is not intended to limit theinvention claimed beyond the requirements of the prior art.

In the drawings there are illustrated by way of example, certainembodiments of the present invention as applied to the apparatus as willbe described in connection with Figure 1. It may be used on a straightdrum spindle, on a tapered drum spindle, or on a combination drumspindle. It will be understood that the invention may be applied toturbine blading as well as to compressor or other blading. As to theparticulars cf Fig. 1, the power plant shown may comprise in general theouter casing structure it open from end to end and having a central corestructure I I which may provide an annular flow passage i2 extendingfore and aft with respect to the aircraft in which it is mounted. Thecentral core structure Il may be supported by the casing structure alongits longitudinal axis and may include a hollow fairing cone IL!-deiining with the forward or left end of the casing lli, as viewed inFig. l, the inlet portion of the flow passage i2.

The core structure also includes on the spindle, the rotor Il of anaxial flow compressor I8, the fixed blades of which may be carried bythe casing lil, the rotor I9 of a turbine 2l, and a conical tailpiece 22which may define with the rear end of the casing structure, a propulsionnozzle 23. The intermediate portion of the core structure between thecompressor and the turbine may comprise an inner wall structure 21%which may house a shaft 25 connecting the turbine rotor i9 andcompressor rotor li and delines with the casing l@ an annular combustionchamber 216. The shaft 25 may be journalled in suitable bearings 25acarried by the outer casing.

The power plant may operate substantially as follows: Air may enter thecasing IQ at the inlet of the iiow passage l2, may be compressed by thecompressor, and may now into a diffuser or convergent portion 35 of thenow passage which effects a further compression of the air. The hotgases or motive fluid comprising the products of combustion and theexcess air heated by the combustion, on leaving the combustion chamber26 may be directed by xed guide vanes or nozzles 38 of the turbine 2|into the blade passage of the turbine rotor I9. The spent gases leavingthe turbine may be discharged through the propulsion nozzle 23 at a highvelocity so that the remaining energy in the motive fluid is availableto propel the aircraft.

The present invention is particularly concerned with the novel meansemployed for preventing axial displacement of the compressor and/orturbine blades with respect to their mounting grooves in their rotordrum.

With reference to Figs. 2 to 4 inclusive, there is shown a rotor drumsuch as may be employed in the straight portions of the spindle justdescribed. The blade portion of the blading proper,` as shown, is purelyfanciful and happens to be in the form of an impeller vane assembly.rThe invention may also be applied to a turbine bucket which maybecarried, for instance, 'on the straightturbine drum of Figure 1.

The blade portions 40,'42, and 4t, Ias shown, are'fadapted to t on acylindrical strip or segmenti incorporated on the'face of the com'-pressor drum. This strip :it may be flanked by two'congruent strips o'rsegments'll and 5B whichv may vbefated 01T plain.' The blade-holdingstrip may .be provided, however, .at its periphery with radiating teeth52, 5t, and, which may carry at their tip or crest, transverse' lugsshown at 58.

Successive teeth suchias54 and 56 therebymay dene transverse T-slotshaving an enlarged groove portion B and a narrow neck-like -portion 62.lThese slots penetrate from the plane represented by the crest of the'teeth down to a depth which may be on a lower level with theplain'lstrips such as at 46. This groove or slot is frequently referredto in the elastic fluid industries as being of the keyholetype.

As may be observed vparticularly in Fig. 2, theselgrooves whileextending generally in an axial direction may be inclined somewhat tothe longitudinal axis of the spindle -They may be cut so as to havestraight walls, yet they do not` affordstraight side entry even thoughthey are opento side entry of a description. `The blade proper :i2 maybe observed to comprise a vane assembly or blade portion S and a rootthroat portion The throat portion G6 may terminate in an enlarged endflange 58 givingit in effect a T appearance, adaptedto be 'received bythe groove 6U.

As Yto its manufacture,'each`blade may, for example; be milled from asolid-piece of steel, bronze, Monel, stellite or other metal. The crosssectional form of the blades andthe manner-in which they are tangedlinto slots" inthe rotor drum are not necessarily new.V -Since theirslots arefinclined -at an acute angleto the length of thestrip, theblades are adaptedv for insertion in side entry at an oblique angle; Theblade may beplaced in the'recess or relieved area represented by strip45 Aand then forced at an angle to the spindle axis into 'thecounterpart slot.- The lugs 58 provide a centripetal shoulderarrangement whereby the roots and blades are secured against'centrifugalforcesacting on'them' during operation.

To prevent axial shiftof the blades'once installed, ller rings suchas atI0 andlZ may be provided.V VThese rings-may-consist Aof at'strips.equal'in thickness approximately. to the working` depth `of thebladeslots justdescribed. .The

filler-rings may be adapted-to t in the bottom-.

of the recess formed by 45 and may comprise a series of arcuatesegments. As appears in Fig. 2, the segments may abut one another anddepending on their length expose a suitable number of blades toinsertion or removal upon being detached.

The particular segments shown in Fig. 3 have been provided with anaperture '.'8 adapted to register with a tapped bere SEB provided instrip Sil 4The segment may be fastened to the cylindrical strip 5G by adetachable screw means, such as shown at 32, or some other commonexpedient. In order to remove one of the blades the filler segment ofthe ring on either side as involved, maybe removed and the blade quicklyslipped out into the open over strip 5G. Then a new blade may be4inserted and the segment re-installed. These i'llier rings serve notonly to lock the blades in place but provide a smooth surface to defineand direct the flow of the fluid passing through theturbine. Thisattachment, perfectly suitable for use on a turbine rotor, may be usedtoo throughout an entire compressor rotor, the idea also being that theouter casing Walls will be tapered inwardly to accommodate the region ofthe shorter blades as in the diffuser area.

For another application of the invention, shownin Figs. 5 and 6 is atapered type drum. This particular adaptation may be employed as well ina combination straight-tapered drum for a compressor or in a turbinerotor where diierentstages of blading are used. In any case, theouter-housing Sii may have an axially straight configuration while thedrum may have a flare imparted to it in order to accommodate thediminishing sized blades The blade represented at 85 happens toincorporate the impellern type. It comprises a vane assembly or bladeportion 88' which may be adapted to fit in a holding strip'or segment 92formed in the face of the rotor drum. Segment S2 may be flanged oneither side by -a segmentor strip Si) and 94 which provide-an outwardlyfacing plain cylindrical surface. Strip 953 may be seen to have astepped relation to strips 92 and 915, with strip Sil lying at theunrelieved end of the slot and strip 92 and on level with the tip.

The actual slot and root arrangement is similar in detail to structurepreviously described. Along the base circle of the blade holding slot isaligned the surface of strip 99. Provided for each one of these sectionssuch as S and S2 may be a transverse ange or rib 96 to provide forcentrifugal and other forces exerted on the drum duringoperation. On thestep S4 may be seen a Wedge-shaped nller ring 9S. Since access to thestep gli is substantially unobstructed, this ring S8 is preferably ofunitary form and may be inserted as one piece over the teeth of strip 92and onto the step.

The wedge-shaped llers 98 and H33. are arranged to present a frustoconical surface such as will" converge with casing 815. The surface maybe of regular selected pitch and is preferably smooth. Pitched in withthis conguration there may be provided a baiile 84 mounted on the'bladeassembly 88." The wedges and baffle may. cooperate to present a regularinclined surfaceanddirect the-gas into a path of decreasing orincreasing-girth as the case may be. The baille lli may have its edges|05 trimmed on a bias'the samer aslis the root portion of the bladewhereby `it may-be inserted/into position'at the samer angle asisthebladeJU-This inclination of course is related to and dependent uponthe angle of incidence at which the blade portions are designed to beset. The edge |05 of the baille is adapted to abut the bailie of theblade next succeeding and present an uninterrupted ring around the rotordrum. Only a small change in the conguration of the actual blade portionmay be all that is necessary to convert this saine structure into anordinary turbine bucket. The baille in that instance will provide meansfor expanding the gases in going from one blade stage to the next.

It will be observed that such an attachment as is used on the taperedrotor is not susceptible of blade insertion from either side as was thestraight rotor, although side entry may be used. In assemblage theannular ring on the higher step succeeding will preferably be positionedand then the blade inserted from the plain portion of the lower levelnextl preceding. The blade will then abut against nller rings on eitherside and/or the higher strip such as at 94 on the higher side dependingof course on whether the slot has been extended by undercutting a smalldistance beneath the ller S8. The blades may thus be firmly locked inplace with no opportunity for axial slip or dislodgement.

In practice the present invention may be found to be highly desirablefor use in attaching blades to spindles comprising turbine and blowerrotors, and the like, operating at high speeds since it makes possiblethe mounting of the blades therein without localized weakening of thespindle. The spindle is provided with individual slots for the bladeswhich may therefore be placed in assembled position or removed whenrequired without disturbing adjacent blades. Moreover, each blade beinginserted in an individual slot, the peripheral portion of the spindlemay remain uniformly strong. No part of the slot serving to accommodatea blade is subjected to the wear occasioned by the repeated. insertionof blades into and the moving thereof through a single slot as is thecase in many structures of this type. The

blades will therefore retain their initial ts With- -1 in the slotsindenitely.

What is claimed is:

l. In a gas turbine power plant incorporating elastic fluid utilizingapparatus having an annular ilow passage defined by the combination of acylindrical outer casing, a hollow rotor having a tapered segment in theouter face, the rotor comprising a succession of stepped cylindricalstrips on said tapered segment alternating with conjoined stripsintegral therewith having straight grooves at the periphery disposed atacute angles to the length oi the respective strip, said groovesextending across said strip from one end to the other end thereof, and anumber or moving blades having roots inserted in said grooves, withgenerally sloping deiiecting bailles secured to said blades and adaptedto divide said blades into at least two sections located radiallyoutward of each other, the baffles defining a generally predeterminedpitch cone, and a number oi moving wedge fillers bearingcircumierentially on the stepped cylindrical strips, the fillers ofsuccessive stepped strips presenting their' Wedge faces in generalconformity with said pitch cone and pitching with the appertainingbaffles of the included blades to form said tapered segment.

2. For use in elastic fluid utilizing apparatus of the axial now type,the combination with a hollow rotor having thereabout a succession ofintegral coaxial annular strips of limited width and each bearingthrough slots extending diagonally from one lateral side of the strip tothe other side and undercutting centripetal shoulders thereon, thesuccessive strips being separated by a plain spacing segment of the samelimited width but recessed radially below the succeeding strip, of aplurality of blades having enlarged roots received in said slots withthe enlarged roots engaging the centripetal shoulders, the root of eachblade when assembled being substantially coextensive with the strip towhich it is mounted and as incident to being assembled being receivableon the immediately preceding adjacent segment whereby for assemblage itmay occupy the recess afforded by said adjacent segment preparatory toentry into the root-receiving slot thereof, and a unitary ringconstituting filler means detachably occupying the recess offered byeach segment, the width of the iiller means being substantially the sameas said limited width in common to the strips and segments, said unitaryring constituting said iiller means being adapted to flank the bladesabutting them generally on each side.

3. For use in elastic fluid utilizing apparatus of the axial ow type,the combination with a hollow rotor having thereabout a succession ofintegral coaxial annular strips of limited Width and each bearingthrough slots extending diagonally from one side of the strip to theother and undercutting centripetal shoulders, the successive stripsbeing separated by a plain spacing segment of the same limited width butrecessed radially below the succeeding strip, of a plurality of bladeshaving enlarged roots received in said slots with the enlarged rootsengaging the centripetal shoulders, the root of each blade being whenassembled, substantially coextensive with the width of itsroot-receiving strip and as incident to assembly being receivable on theimmediately preceding adjacent segment whereby for assemblage it mayoccupy the recess afforded by said adjacent segment preparatory to entryinto the root-receiving slot therefor, and ller means detachablyoccupying the recess aiforded by each segment, the Width of the llermeans being substantially the same as said limited width in common tothe strips and segments, said filler means being adapted to flank theblades abutting them generally on each side and comprising a unitary natring of substantially the same depth of thickness as its recess andadapted to slide over the strip preceding for installation onto andremoval from its segment.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,160,281 Price May 30, 1939 2,279,258 Allen et al Apr. 7,1942 2,317,338 Rydmark Apr. 20, 1943 2,415,847 Redding Feb. 18, 19472,452,782 McLeod et al. Nov. 2, 1948 FOREIGN PATENTS Number Country Date22,536 Great Britain Oct. 12, 1906 172,769 Germany July 11, 1906 537,121Great Britain June 10, 1941 OTHER REFERENCES Flight, article entitled,Mamba Unmasked, March 18, 1948, pgs. b to h (p. c only is relied on).

